Bill O'Reilly spinning about Donahue

I just saw the intro to his show tonight and he's trying to say that Phil Donahue broke some golden rule and that's why he flipped out. Here's the transcript. You can see the video here:

DONAHUE: You saw the pictures! (reasonable tone of voice) Now listen - listen. You wouldn't send your children to this war, Bill. O'REILLY (very angry, pointing): My nephew just enlisted in the Army. You don't know what the hell you're talkin' about!!!

DONAHUE: Very good. Very good. Congratulations! You should be proud .. O'REILLY (starts to lose it, shouting, pointing finger, hand shaking): And he's a patriot, so don't denigrate his service or I'll boot you right off the set!!!

DONAHUE: I'm not ... I'm not ... O'REILLY (very, very loud): That boy made a decision to serve his country!!! Do not denigrate him or you're outta here!!!

How did Donahue denigrate his nephew? What rule did Phil violate? Why should I ask these questions?